This dissertation research will identify the risk and protective factors associated with mental health/behavior problems and behavioral functioning in sexual minority adolescents, drawing from an ecological, multi-systems conceptual framework. Sexual minority adolescents (i.e., youths who identify as or believe themselves to be gay, lesbian, or bisexual) constitute a population at risk for mental health and behavioral problems, including substance abuse and suicidality. The prevention of psychopathology and behavior problems in sexual minority adolescents requires understanding the interplay between risk and protective factors in determining their mental health/behavior and behavioral functioning. This information will guide practitioners in developing individual, family, and community-level interventions that will prevent serious mental health and behavior problems, such as substance abuse, suicidality, and depression. This cross-sectional study will gather data via self-administered questionnaires from 200 gay, lesbian, and bisexual adolescents, recruited through multiple methods, about individual, family and community risk and protective factors; mental health and behavior problems; and behavioral functioning. This study aims to: (1) Determine the relationships between potential risk and protective factors and the mental health/behavior problems and behavioral functioning of sexual minority adolescents; and (2) determine how individual, family and community risk and protective factors jointly and interactively influence the mental health/behavior and behavioral functioning of sexual minority adolescents. This dissertation research will provide knowledge of an underserved, high risk population of youths about whom little is understood. The study is unique in its examination of the relationships between multiple risk and protective factors (those unique to the experience of sexual minority adolescents and those shared with other at-risk youths) and mental health/behavior problems and behavioral functioning among gay, lesbian, and bisexual youths.